Myocyte-specific overexpressing HDAC4 promotes myocardial ischemia/reperfusion injury

Hydrogen sulfide plays an important role by regulating microRNA in different ischemia-reperfusion injury

MicroRNAs (miRNAs) are the short endogenous non-coding RNAs that regulate the expression of the target gene at posttranscriptional level through degrading or inhibiting the specific target messenger RNAs (mRNAs). MiRNAs regulate the expression of approximately one-third of protein coding genes, and in most cases inhibit gene expression. MiRNAs have been reported to regulate various biological processes, such as cell proliferation, apoptosis and differentiation. Therefore, miRNAs participate in multiple diseases, including ischemia-reperfusion (I/R) injury. Hydrogen sulfide (H2S) was once considered as a colorless, toxic and harmful gas with foul smelling. However, in recent years, it has been discovered that it is the third gas signaling molecule after carbon monoxide (CO) and nitric oxide (NO), with multiple important biological functions. Increasing evidence indicates that H2S plays a vital role in I/R injury through regulating miRNA, however, the mechanism has not been fully understood. In this review, we summarized the current knowledge about the role of H2S in I/R injury by regulating miRNAs, and analyzed its mechanism in detail.

Targeting histone deacetylase in cardiac diseases

Histone deacetylases (HDAC) catalyze the removal of acetylation modifications on histones and non-histone proteins, which regulates gene expression and other cellular processes. HDAC inhibitors (HDACi), approved anti-cancer agents, emerge as a potential new therapy for heart diseases. Cardioprotective effects of HDACi are observed in many preclinical animal models of heart diseases. Genetic mouse models have been developed to understand the role of each HDAC in cardiac functions. Some of the findings are controversial. Here, we provide an overview of how HDACi and HDAC impact cardiac functions under physiological or pathological conditions. We focus on in vivo studies of zinc-dependent classical HDACs, emphasizing disease conditions involving cardiac hypertrophy, myocardial infarction (MI), ischemic reperfusion (I/R) injury, and heart failure. In particular, we review how non-biased omics studies can help our understanding of the mechanisms underlying the cardiac effects of HDACi and HDAC.

Class I and II Histone Deacetylase Inhibitors as Therapeutic Modulators of Dilated Cardiac Tissue-Derived Mesenchymal Stem/Stromal Cells

The prevalence of dilated cardiomyopathy (DCM) is increasing globally, highlighting the need for innovative therapeutic approaches to prevent its onset. In this study, we examined the energetic and epigenetic distinctions between dilated and non-dilated human myocardium-derived mesenchymal stem/stromal cells (hmMSCs) and assessed the effects of class I and II HDAC inhibitors (HDACi) on these cells and their cardiomyogenic differentiation. Cells were isolated from myocardium biopsies using explant outgrowth methods. Mitochondrial and histone deacetylase activities, ATP levels, cardiac transcription factors, and structural proteins were assessed using flow cytometry, PCR, chemiluminescence, Western blotting, and immunohistochemistry. The data suggest that the tested HDAC inhibitors improved acetylation and enhanced the energetic status of both types of cells, with significant effects observed in dilated myocardium-derived hmMSCs. Additionally, the HDAC inhibitors activated the cardiac transcription factors Nkx2-5, HOPX, GATA4, and Mef2C, and upregulated structural proteins such as cardiac troponin T and alpha cardiac actin at both the protein and gene levels. In conclusion, our findings suggest that HDACi may serve as potential modulators of the energetic status and cardiomyogenic differentiation of human heart hmMSCs. This avenue of exploration could broaden the search for novel therapeutic interventions for dilated cardiomyopathy, ultimately leading to improvements in heart function.

Roles of Histone Deacetylase 4 in the Inflammatory and Metabolic Processes

Histone deacetylase 4 (HDAC4), a class IIa HDAC, has gained attention as a potential therapeutic target in treating inflammatory and metabolic processes based on its essential role in various biological pathways by deacetylating non-histone proteins, including transcription factors. The activity of HDAC4 is regulated at the transcriptional, post-transcriptional, and post-translational levels. The functions of HDAC4 are tissue-dependent in response to endogenous and exogenous factors and their substrates. In particular, the association of HDAC4 with non-histone targets, including transcription factors, such as myocyte enhancer factor 2, hypoxia-inducible factor, signal transducer and activator of transcription 1, and forkhead box proteins, play a crucial role in regulating inflammatory and metabolic processes. This review summarizes the regulatory modes of HDAC4 activity and its functions in inflammation, insulin signaling and glucose metabolism, and cardiac muscle development.

lncRNA TUG1 as potential novel biomarker for prognosis of cardiovascular diseases

Globally, cardiovascular diseases (CVDs) are among the leading causes of death. In light of the high prevalence and mortality of CVDs, it is imperative to understand the molecules involved in CVD pathogenesis and the signaling pathways that they initiate. This may facilitate the development of more precise and expedient diagnostic techniques, the identification of more effective prognostic molecules and the identification of potential therapeutic targets. Numerous studies have examined the role of lncRNAs, such as TUG1, in CVD pathogenesis in recent years. According to this review article, TUG1 can be considered a biomarker for predicting the prognosis of CVD.

Leucine Supplementation Improves Diastolic Function in HFpEF by HDAC4 Inhibition

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome associated with a high morbidity and mortality rate. Leucine supplementation has been demonstrated to attenuate cardiac dysfunction in animal models of cachexia and heart failure with reduced ejection fraction (HFrEF). So far, no data exist on leucine supplementation on cardiac function in HFpEF. Thus, the current study aimed to investigate the effect of leucine supplementation on myocardial function and key signaling pathways in an established HFpEF rat model. Female ZSF1 rats were randomized into three groups: Control (untreated lean rats), HFpEF (untreated obese rats), and HFpEF_Leu (obese rats receiving standard chow enriched with 3% leucine). Leucine supplementation started at 20 weeks of age after an established HFpEF was confirmed in obese rats. In all animals, cardiac function was assessed by echocardiography at baseline and throughout the experiment. At the age of 32 weeks, hemodynamics were measured invasively, and myocardial tissue was collected for assessment of mitochondrial function and for histological and molecular analyses. Leucine had already improved diastolic function after 4 weeks of treatment. This was accompanied by improved hemodynamics and reduced stiffness, as well as by reduced left ventricular fibrosis and hypertrophy. Cardiac mitochondrial respiratory function was improved by leucine without alteration of the cardiac mitochondrial content. Lastly, leucine supplementation suppressed the expression and nuclear localization of HDAC4 and was associated with Protein kinase A activation. Our data show that leucine supplementation improves diastolic function and decreases remodeling processes in a rat model of HFpEF. Beneficial effects were associated with HDAC4/TGF-β1/Collagenase downregulation and indicate a potential use in the treatment of HFpEF.

Acetylation, ferroptosis, and their potential relationships: Implications in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a serious complication affecting the prognosis of patients with myocardial infarction and can cause cardiac arrest, reperfusion arrhythmias, no-reflow, and irreversible myocardial cell death. Ferroptosis, an iron-dependent, peroxide-driven, non-apoptotic form of regulated cell death, plays a vital role in reperfusion injury. Acetylation, an important post-translational modification, participates in many cellular signaling pathways and diseases, and plays a pivotal role in ferroptosis. Elucidating the role of acetylation in ferroptosis may therefore provide new insights for the treatment of MIRI. Here, we summarized the recently discovered knowledge about acetylation and ferroptosis in MIRI. Finally, we focused on the acetylation modification during ferroptosis and its potential relationship with MIRI.

Knockdown of histone deacetylase 9 attenuates sepsis-induced myocardial injury and inflammatory response

Myocardial cell damage is associated with apoptosis and excessive inflammatory response in sepsis. Histone deacetylases (HDACs) are implicated in the progression of heart diseases. This study aims to explore the role of histone deacetylase 9 (HDAC9) in sepsis-induced myocardial injury. Lipopolysaccharide (LPS)-induced Sprague Dawley rats and cardiomyocyte line H9C2 were used as models in vivo and in vitro. The results showed that HDAC9 was significantly upregulated after LPS stimulation, and HDAC9 knockdown remarkably improved cardiac function, as evidenced by decreased left ventricular internal diameter end diastole (LVEDD) and left ventricular internal diameter end systole (LVESD), and increased fractional shortening (FS)% and ejection fraction (EF)%. In addition, HDAC9 silencing alleviated release of inflammatory cytokines (tumor necrosis factor-α (TNF-α), IL-6 and IL-1β) and cardiomyocyte apoptosis in vivo and in vitro. Furthermore, HDAC9 inhibition was proved to suppress nuclear factor-kappa B (NF-κB) activation with reducing the levels of p-IκBα and p-p65, and p65 nuclear translocation. Additionally, interaction between miR-214-3p and HDAC9 was determined through bioinformatics analysis, RT-qPCR, western blot and dual luciferase reporter assay. Our data revealed that miR-214-3p directly targeted the 3'UTR of HDAC9. Our findings demonstrate that HDAC9 suppression ameliorates LPS-induced cardiac dysfunction by inhibiting the NF-κB signaling pathway and presents a promising therapeutic agent for the treatment of LPS-stimulated myocardial injury.

Epigenetic regulation in myocardial infarction: Non-coding RNAs and exosomal non-coding RNAs

Myocardial infarction (MI) is one of the leading causes of deaths globally. The early diagnosis of MI lowers the rate of subsequent complications and maximizes the benefits of cardiovascular interventions. Many efforts have been made to explore new therapeutic targets for MI, and the therapeutic potential of non-coding RNAs (ncRNAs) is one good example. NcRNAs are a group of RNAs with many different subgroups, but they are not translated into proteins. MicroRNAs (miRNAs) are the most studied type of ncRNAs, and have been found to regulate several pathological processes in MI, including cardiomyocyte inflammation, apoptosis, angiogenesis, and fibrosis. These processes can also be modulated by circular RNAs and long ncRNAs via different mechanisms. However, the regulatory role of ncRNAs and their underlying mechanisms in MI are underexplored. Exosomes play a crucial role in communication between cells, and can affect both homeostasis and disease conditions. Exosomal ncRNAs have been shown to affect many biological functions. Tissue-specific changes in exosomal ncRNAs contribute to aging, tissue dysfunction, and human diseases. Here we provide a comprehensive review of recent findings on epigenetic changes in cardiovascular diseases as well as the role of ncRNAs and exosomal ncRNAs in MI, focusing on their function, diagnostic and prognostic significance.

Role of Scl39a13/ZIP13 in cardiovascular homeostasis

Zinc plays a critical role in many physiological processes, and disruption of zinc homeostasis induces various disorders, such as growth retardation, osteopenia, immune deficiency, and inflammation. However, how the imbalance in zinc homeostasis leads to heart disease is not yet fully understood. Cardiovascular diseases are a major cause of death worldwide, and the development of novel therapeutic targets to treat it is urgently needed. We report that a zinc transporter, ZIP13, regulates cardiovascular homeostasis. We found that the expression level of Zip13 mRNA was diminished in both primary neonatal cardiomyocytes and mouse heart tissues treated with the cardiotoxic agent doxycycline. Primary neonatal cardiomyocytes from Zip13 gene-knockout (KO) mice exhibited abnormal irregular arrhythmic beating. RNA-seq analysis identified 606 differentially expressed genes in Zip13-KO mouse-derived primary neonatal cardiomyocytes and Gene ontology (GO) analysis revealed that both inflammation- and cell adhesion-related genes were significantly enriched. In addition, telemetry echocardiography analysis suggested that arrhythmias were likely to occur in Zip13-KO mice, in which elevated levels of the cardiac fibrosis marker Col1a1, vascular inflammation-related gene eNOS, and Golgi-related molecule GM130 were observed. These results indicate the physiological importance of ZIP13-it maintains cardiovascular homeostasis by resolving inflammation and stress response. Our findings suggest that optimizing ZIP13 expression and/or function may improve cardiovascular disease management.

Histone methyltransferase KMT2D contributes to the protection of myocardial ischemic injury

Histone H3 lysine 4 (H3K4) methyltransferase 2D (KMT2D) plays an important role in cell development in early life. However, the function of KMT2D in adult cells such as cardiomyocytes or neurons has not been reported. In this study, cardiomyocyte-specific KMT2D knockout (KMT2D-cKO) and control (KMT2D-Ctl) mice were exposed to sham or myocardial ischemia (MI) surgery. Depletion of KMT2D aggravated the ischemic area, led to the increased mortality (26.5% in KMT2D-cKO vs 12.5% in KMT2D-Ctl) of the mice, and weakened the left ventricular systolic function. RNA-seq analysis in cardiac tissues identified genes whose expression was changed by MI and KMT2D deletion. Combined with the genome-wide association study (GWAS) analysis, cardiac disease-associated genes Rasd1, Thsd7a, Ednra, and Tns1 were identified. The expression of the Rasd1 was significantly decreased by MI or the loss of KMT2D in vivo. Meanwhile, ChIP assays demonstrated that either MI or loss of KMT2D attenuated monomethylated H3K4 (H3K4me1) enrichment on the enhancer of Rasd1. By generating a KMT2D knockout (H9C2-KO) H9C2 monoclone, we verified that the expression of Rasd1 was controlled by KMT2D, and the expression of Rasd1 was decreased by serum starvation but not low-(O₂) treatment in H9C2 cells. KMT2D has a protective effect on ischemic myocardium by regulating cardiac disease-associated genes including Rasd1. KMT2D is required for the H3K4me1 deposition on the enhancer of Rasd1. Our data for the first time suggest that KMT2D-mediated Rasd1 expression may play an important protective effect on adult cells during nutritional deficiency caused by ischemic injury.

Blunting TRPML1 channels protects myocardial ischemia/reperfusion injury by restoring impaired cardiomyocyte autophagy

Accumulating evidence suggests that autophagy dysfunction plays a critical role in myocardial ischemia/reperfusion (I/R) injury. However, the underling mechanism of malfunctional autophagy in the cardiomyocytes subjected to I/R has not been well defined. As a result, there is no effective therapeutic option by targeting autophagy to prevent myocardial I/R injury. Here, we used both an in vitro and an in vivo I/R model to monitor autophagic flux in the cardiomyocytes, by exposing neonatal rat ventricular myocytes to hypoxia/reoxygenation and by subjecting mice to I/R, respectively. We observed that the autophagic flux in the cardiomyocytes subjected to I/R was blocked in both in vitro and in vivo models. Down-regulating a lysosomal cationic channel, TRPML1, markedly restored the blocked myocardial autophagic flux induced by I/R, demonstrating that TRPML1 directly contributes to the blocked autophagic flux in the cardiomyocytes subjected to I/R. Mechanistically, TRPML1 is activated secondary to ROS elevation following ischemia/reperfusion, which in turn induces the release of lysosomal zinc into the cytosol and ultimately blocks the autophagic flux in cardiomyocytes, presumably by disrupting the fusion between autophagosomes and lysosomes. As a result, the inhibited myocardial autophagic flux induced by TRPML1 disrupted mitochondria turnover and resulted in mass accumulation of damaged mitochondria and further ROS release, which directly led to cardiomyocyte death. More importantly, pharmacological and genetic inhibition of TRPML1 channels greatly reduced infarct size and rescued heart function in mice subjected to I/R in vivo by restoring impaired myocardial autophagy. In summary, our study demonstrates that secondary to ROS elevation, activation of TRPML1 results in autophagy inhibition in the cardiomyocytes subjected to I/R, which directly leads to cardiomyocyte death by disrupting mitochondria turnover. Therefore, targeting TRPML1 represents a novel therapeutic strategy to protect against myocardial I/R injury.

The circRNA CNEACR regulates necroptosis of cardiomyocytes through Foxa2 suppression

Circular RNAs (circRNAs) are differentially expressed in various cardiovascular disease including myocardial ischemia-reperfusion (I/R) injury. However, their functional impact on cardiomyocyte cell death, in particular, in necrotic forms of death remains elusive. In this study, we found that the level of mmu_circ_000338, a cardiac- necroptosis-associated circRNA (CNEACR), was reduced in hypoxia-reoxygenation (H/R) exposed cardiomyocytes and I/R-injured mice hearts. The enforced expression of CNEACR attenuated the necrotic form of cardiomyocyte death caused by H/R and suppressed of myocardial necrosis in I/R injured mouse heart, which was accompanied by a marked reduction of myocardial infarction size and improved cardiac function. Mechanistically, CNEACR directly binds to histone deacetylase (HDAC7) in the cytoplasm and interferes its nuclear entry. This leads to attenuation of HDAC7-dependent suppression of forkhead box protein A2 (Foxa2) transcription, which can repress receptor-interacting protein kinase 3 (Ripk3) gene by binding to its promoter region. In addition, CNEACR-mediated upregulation of FOXA2 inhibited RIPK3-dependent necrotic/necroptotic death of cardiomyocytes. Our study reveals that circRNAs such as CNEACR can regulate the cardiomyocyte necroptosis associated activity of HDACs, promotes cell survival and improves cardiac function in I/R-injured heart. Hence, the CNEACR/HDAC7/Foxa2/ RIPK3 axis could be an efficient target for alleviating myocardial damage caused by necroptotic death in ischemia heart diseases.

Sevoflurane protects mice from cerebral ischemic injury by regulating microRNA-203-3p/HDAC4/Bcl-2 axis

Sevoflurane (Sevo) is neuroprotective in ischemic injury, but its specific mechanism in the disease from microRNA-203-3p/histone deacetylases 4/B-cell lymphoma 2 (miR-203-3p/HDAC4/Bcl-2) axis asks for a comprehensive explanation. A middle cerebral artery occlusion (MCAO) mouse model was established by nylon suture method. miR-203-3p and HDAC4 expression was measured in mouse brain tissues. The MCAO mice were exposed to Sevo or injected with miR-203-3p- or HDAC4-related plasmids. In response to Sevo treatment or plasmid interference, neurological function, brain pathology, neuronal apoptosis and inflammation were determined. The interactions of miR-203-3p and HDAC4, and HDAC4 and Bcl-2 were verified. MCAO mice presented down-regulated miR-203-3p and up-regulated HDAC4. Sevo improved neurological function, brain pathological damage and reduced neuronal apoptosis and inflammation in MCAO mice, while overexpressing miR-203-3p further enhanced those effects. HDAC4 overexpression antagonized the impacts of miR-203-3p up-regulation on MCAO mice. The targeting relation existed between miR-203-3p and HDAC4, as well as between HDAC4 and Bcl-2. It is clearly elucidated that miR-203-3p enhances the protective effects of Sevo on MCAO mice through elevating Bcl-2 and down-regulating HDAC4, potentially and clinically offering an effective treatment method with Sevo for cerebral ischemic injury.

microRNA-124-3p attenuates myocardial injury in sepsis via modulating SP1/HDAC4/HIF-1α axis

Sepsis-induced cardiac dysfunction can lead to death in sepsis. In this case, we targeted to explore in detail the relative mechanism of microRNA (miR)-124-3p in sepsis-induced myocardial injury via the specific protein 1/histone deacetylase 4/hypoxia-inducing factor 1α (SP1/HDAC4/HIF-1α) axis. Septic rats were modeled by cecal ligation puncture while in vitro septic cardiomyocyte H9C2 were induced by lipopolysaccharide (LPS). miR-124-3p/SP1/HDAC4/HIF-1α expression levels in myocardial tissues of septic rats and LPS-treated H9C2 cells were measured. miR-124-3p overexpression and SP1 silencing assays were implemented on LPS-treated H9C2 cells to explore theirs actions in inflammation, oxidative stress and cell apoptosis. The interactions of miR-124-3p, SP1, and HDAC4 were testified. miR-124-3p was lowly expressed while SP1, HDAC4, and HIF-1α were highly expressed in sepsis. Upregulation of miR-124-3p ameliorated inflammation, oxidative stress, and apoptosis of LPS-treated H9C2 cells. Silencing SP1 improved LPS-induced damage to cardiomyocytes. miR-124-3p targeted SP1 and HDAC4 interacted with SP1. SP1 overexpression antagonized miR-124-3p upregulation-induced improvements in LPS-induced cardiomyocyte damage. This study illustrates that miR-124-3p improves myocardial injury in septic rats through targeted regulation of SP1 to mediate HDAC4/HIF-1α.

Targeting Epigenetics and Non-coding RNAs in Myocardial Infarction: From Mechanisms to Therapeutics

Myocardial infarction (MI) is a complicated pathology triggered by numerous environmental and genetic factors. Understanding the effect of epigenetic regulation mechanisms on the cardiovascular disease would advance the field and promote prophylactic methods targeting epigenetic mechanisms. Genetic screening guides individualised MI therapies and surveillance. The present review reported the latest development on the epigenetic regulation of MI in terms of DNA methylation, histone modifications, and microRNA-dependent MI mechanisms and the novel therapies based on epigenetics.

Cardiomyogenic Differentiation Potential of Human Dilated Myocardium-Derived Mesenchymal Stem/Stromal Cells: The Impact of HDAC Inhibitor SAHA and Biomimetic Matrices

Dilated cardiomyopathy (DCM) is the most common type of nonischemic cardiomyopathy characterized by left ventricular or biventricular dilation and impaired contraction leading to heart failure and even patients’ death. Therefore, it is important to search for new cardiac tissue regenerating tools. Human mesenchymal stem/stromal cells (hmMSCs) were isolated from post-surgery healthy and DCM myocardial biopsies and their differentiation to the cardiomyogenic direction has been investigated in vitro. Dilated hmMSCs were slightly bigger in size, grew slower, but had almost the same levels of MSC-typical surface markers as healthy hmMSCs. Histone deacetylase (HDAC) activity in dilated hmMSCs was 1.5-fold higher than in healthy ones, which was suppressed by class I and II HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) showing activation of cardiomyogenic differentiation-related genes alpha-cardiac actin (ACTC1) and cardiac troponin T (TNNT2). Both types of hmMSCs cultivated on collagen I hydrogels with hyaluronic acid (HA) or 2-methacryloyloxyethyl phosphorylcholine (MPC) and exposed to SAHA significantly downregulated focal adhesion kinase (PTK2) and activated ACTC1 and TNNT2. Longitudinal cultivation of dilated hmMSC also upregulated alpha-cardiac actin. Thus, HDAC inhibitor SAHA, in combination with collagen I-based hydrogels, can tilt the dilated myocardium hmMSC toward cardiomyogenic direction in vitro with further possible therapeutic application in vivo.

Effect of Tai Chi on cardiac function in patients with myocardial infarction: A protocol for a randomized controlled trial

BACKGROUND

Myocardial infarction is 1 of the most serious cardiovascular diseases. Early interventional therapy preserves the cardiac function of patients with myocardial infarction to the greatest extent, but it is far from meeting people's need only limited to cardiac revascularization. It is also necessary to help patients improve their quality of life, exercise tolerance, and reduce the incidence of acute cardiac recurrence as much as possible. All these depend on cardiac rehabilitation (CR) are based on exercise. Early and correct CR helps to improve the patient's heart function and improve living standards. Traditional Chinese exercise Tai Chi as an alternative form of CR has gradually become popular, but it lacks large samples and high-quality clinical studies to verify it. This study aims to explore the effect of Tai Chi on the cardiac function of patients with myocardial infarction, and to provide a strong basis for patients to choose which CR exercise.

METHODS

This is a prospective randomized controlled trial. 272 patients with myocardial infarction will be randomly divided into an experimental group and a control group according to 1:1, with 136 cases in each group. The control group: conventional treatment; the experimental group: increase Tai Chi exercise on the basis of the control group. Both groups will receive standard treatment for 24 weeks and will be followed up for 3 months. Observation indicators include: total effective rate, 6 minutes walking test, brain natriuretic peptide, left ventricular ejection fraction, the adverse reaction rate, etc. The data will be analyzed by using SPSS 25.0 software.

DISCUSSION

This study will evaluate the effect of Tai Chi on the cardiac function of patients with myocardial infarction. The results of this test will provide clinical evidence for patients to choose which CR exercise.

TRIAL REGISTRATION

OSF Registration number: DOI 10.17605/OSF.IO/QKWDP.

Histone deacetylase HDAC4 participates in the pathological process of myocardial ischemia-reperfusion injury via MEKK1/JNK pathway by binding to miR-206

Histone deacetylases (HDACs) and microRNAs (miRs) have been reported to exert pivotal roles on the pathogenesis of myocardial ischemia-reperfusion injury (MIRI). Therefore, the present study was performed to define the underlying role of HDAC4 and miR-206 in the pathological process of MIRI. An IRI rat model was established. The interaction between HDAC4 and the promoter region of miR-206 was determined using ChIP, and that between miR-206 and mitogen-activated protein kinase kinase kinase 1 (MEKK1) was determined using dual luciferase reporter gene assay. After the loss- or gain-of-function assay in cardiomyocytes, western blot analysis, RT-qPCR, TUNEL, and ELISA assay were performed to define the roles of HDAC4, miR-206, and MEKK1. Up-regulation of HDAC4 and down-regulation of miR-206 occurred in rat myocardial tissues and cardiomyocytes in MIRI. HDAC4 down-regulation or miR-206 up-regulation contributed to reduced cell apoptosis and the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and malondialdehyde (MDA), while elevating the superoxide dismutase (SOD) and glutathione (GSH) contents. Meanwhile, HDAC4 silencing promoted the expression of miR-206, which targeted and negatively regulated MEKK1. Then inhibition of JNK phosphorylation reduced the cardiomyocyte apoptosis to alleviate MIRI. Coherently, HDAC4 silencing could up-regulate the expression of miR-206 to reduce cardiomyocyte apoptosis and inhibit oxidative stress, and exerting a protective effect on MIRI via the MEKK1/JNK pathway.

The potentials of distinct functions of autophagy to be targeted for attenuation of myocardial ischemia/reperfusion injury in preclinical studies: an up-to-date review

Despite remarkable advances in our knowledge about the function of autophagy in myocardial ischemia/reperfusion (I/R) injury, the debate continues over whether autophagy is protective or deleterious in cardiac I/R. Due to the complexity of autophagy signaling, autophagy can play a dual role in the pathological processes of myocardial I/R injury. Thus, more researches are needed to shed light on the complex roles of autophagy in cardioprotection for the future clinical development. Such researches can lead to the finding of new therapeutic strategies for improving cardiac I/R outcomes in patients. Several preclinical studies have targeted autophagy flux as a beneficial strategy against myocardial I/R injury. In this review, we aimed to discuss the complex contribution of autophagy in myocardial I/R injury, as well as the therapeutic agents that have been shown to be useful in reducing myocardial I/R injury by targeting autophagy. For this reason, we provided an updated summary of the data from in vivo, ex vivo, and in vitro experimental studies about the therapeutic agents that exert positive effects against myocardial I/R injury by modulating autophagy flux. By addressing these valuable studies, we try to provide a motivation for the promising hypothesis of "autophagy modulation as a therapeutic strategy against cardiac I/R" in the future clinical studies.

Functional Duality of Chondrocyte Hypertrophy and Biomedical Application Trends in Osteoarthritis

Chondrocyte hypertrophy is one of the key indicators in the progression of osteoarthritis (OA). However, compared with other OA indications, such as cartilage collapse, sclerosis, inflammation, and protease activation, the mechanisms by which chondrocyte hypertrophy contributes to OA remain elusive. As the pathological processes in the OA cartilage microenvironment, such as the alterations in the extracellular matrix, are initiated and dictated by the physiological state of the chondrocytes, in-depth knowledge of chondrocyte hypertrophy is necessary to enhance our understanding of the disease pathology and develop therapeutic agents. Chondrocyte hypertrophy is a factor that induces OA progression; it is also a crucial factor in the endochondral ossification. This review elaborates on this dual functionality of chondrocyte hypertrophy in OA progression and endochondral ossification through a description of the characteristics of various genes and signaling, their mechanism, and their distinguishable physiological effects. Chondrocyte hypertrophy in OA progression leads to a decrease in chondrogenic genes and destruction of cartilage tissue. However, in endochondral ossification, it represents an intermediate stage at the process of differentiation of chondrocytes into osteogenic cells. In addition, this review describes the current therapeutic strategies and their mechanisms, involving genes, proteins, cytokines, small molecules, three-dimensional environments, or exosomes, against the OA induced by chondrocyte hypertrophy. Finally, this review proposes that the contrasting roles of chondrocyte hypertrophy are essential for both OA progression and endochondral ossification, and that this cellular process may be targeted to develop OA therapeutics.

Role of epigenetic regulation in myocardial ischemia/reperfusion injury

Nowadays acute myocardial infarction (AMI) is a serious cardiovascular disease threatening the human life and health worldwide. The most effective treatment is to quickly restore coronary blood flow through revascularization. However, timely revascularization may lead to reperfusion injury, thereby reducing the clinical benefits of revascularization. At present, no effective treatment is available for myocardial ischemia/reperfusion injury. Emerging evidence indicates that epigenetic regulation is closely related to the pathogenesis of myocardial ischemia/reperfusion injury, indicating that epigenetics may serve as a novel therapeutic target to ameliorate or prevent ischemia/reperfusion injury. This review aimed to briefly summarize the role of histone modification, DNA methylation, noncoding RNAs, and N⁶-methyladenosine (m⁶A) methylation in myocardial ischemia/reperfusion injury, with a view to providing new methods and ideas for the research and treatment of myocardial ischemia/reperfusion injury.

The regulation of protein acetylation influences the redox homeostasis to protect the heart

The cellular damage caused by redox imbalance is involved in the pathogenesis of many cardiovascular diseases. Besides, redox imbalance is related to the alteration of protein acetylation processes, causing not only chromatin remodeling but also disturbances in so many processes where protein acetylation is involved, such as metabolism and signal transduction. The modulation of acetylases and deacetylases enzymes aids in maintaining the redox homeostasis, avoiding the deleterious cellular effects associated with the dysregulation of protein acetylation. Of note, regulation of protein acetylation has shown protective effects to ameliorate cardiovascular diseases. For instance, HDAC inhibition has been related to inducing cardiac protective effects and it is an interesting approach to the management of cardiovascular diseases. On the other hand, the upregulation of SIRT protein activity has also been implicated in the relief of cardiovascular diseases. This review focuses on the major protein acetylation modulators described, involving pharmacological and bioactive compounds targeting deacetylase and acetylase enzymes contributing to heart protection through redox homeostasis.

HDAC5 inhibition reduces angiotensin II-induced vascular contraction, hypertrophy, and oxidative stress in a mouse model

Non-specific histone deacetylase (HDAC) inhibition reduces high blood pressure in essential hypertensive animal models. However, the exact HDAC isoforms that play a critical role in controlling hypertension are not known. Here, we investigated the role of HDAC5 in vascular contraction, hypertrophy, and oxidative stress in the context of angiotensin II (Ang II)-induced hypertension. Genetic deletion of HDAC5 and treatment with class IIa HDAC inhibitors (TMP269 and TMP195) prevented Ang II-induced increases in blood pressure and arterial wall thickness. Hdac5-knockout mice were also resistant to the thromboxane A2 agonist (U46619)-induced vascular contractile response. Furthermore, the expression of Rho-associated protein kinase (ROCK) 2 was downregulated in the aortas of Ang II-treated Hdac5-knockout mice. Knockdown of HDAC5, RhoA, or ROCK2 reduced collagen gel contraction, whereas silencing of ROCK1 increased it. VSMC hypertrophy reduced on knocking down HDAC5, ROCK1, and ROCK2. Here we showed that genetic deletion of HDAC5 and pharmacological inhibition of class IIa HDACs ameliorated Ang II-induced ROS generation. Moreover, ROCK1 and ROCK2, the downstream targets of HDAC5, influenced ROS generation. The relative protein levels of HDAC5, ROCK1, and ROCK2 were increased both in the cytoplasm and nuclear fraction in response to Ang II stimulation in vascular smooth muscle cells. Inhibition of HDAC5 expression or activity reduced vascular hypertrophy, vasoconstriction, and oxidative stress in the Ang II-induced hypertension model. These findings indicate that HDAC5 may serve as a potential target in the treatment of hypertension.

LncRNA TUG1 competitively binds to miR-340 to accelerate myocardial ischemia-reperfusion injury

The aberrant expression of long noncoding RNA (lncRNA) taurine-upregulated gene 1 (TUG1) has been previously associated with myocardial ischemia-reperfusion injury (MIRI), but the underlying molecular mechanisms remain elusive. The current study aimed to clarify the functional role of TUG1/microRNA (miR)-340/histone deacetylase 4 (HDAC4)/β-catenin/glucose transporter type 1 (GLUT1) axes in MIRI. The database-based analyses performed predicted the downstream factors of lncRNA TUG1. In the MIRI mouse models and hypoxia/reoxygenation (H/R)-induced cardiomyocyte models, the expression of TUG1/miR-340/HDAC4/β-catenin/GLUT1 was manipulated to examine their effects on the infarction area, cardiomyocyte viability and apoptosis employing the Evans blue/TTC double staining, CCK-8 and TUNEL assays. Furthermore, the dual luciferase reporter and RIP assays verified the binding affinity of miR-340 to TUG1 and HDAC4. Subsequently, a negative correlation between miR-340 and TUG1 or HDAC4 expression was identified in myocardial tissues of MIRI mice and H/R-induced cardiomyocyte models, along with a positive correlation between TUG1 and HDAC4. Additionally, it was established that TUG1 bound to miR-340, and miR-340 targeted HDAC4. TUG1 upregulated HDAC4 expression, thereby promoting MIRI in the mouse models. HDAC4 was proven to repress the expression of β-catenin and its target gene GLUT1. Moreover, the in vivo experiments validated that the inhibition of TUG1/miR-340/HDAC4/β-catenin/GLUT1 axes alleviated MIRI in mice. Collectively, the current study uncovered the role of TUG1/miR-340/HDAC4/β-catenin/GLUT1 axes in MIRI mouse models and H/R-induced cardiomyocyte models which may be a potential therapeutic target for MIRI treatment.

Class IIa HDAC inhibitor TMP195 alleviates lipopolysaccharide-induced acute kidney injury

Sepsis-associated acute kidney injury (SA-AKI) is associated with high mortality rates, but clinicians lack effective treatments except supportive care or renal replacement therapies. Recently, histone deacetylase (HDAC) inhibitors have been recognized as potential treatments for acute kidney injury and sepsis in animal models; however, the adverse effect generated by the use of pan inhibitors of HDACs may limit their application in people. In the present study, we explored the possible renoprotective effect of a selective class IIa HDAC inhibitor, TMP195, in a murine model of SA-AKI induced by lipopolysaccharide (LPS). Administration of TMP195 significantly reduced increased serum creatinine and blood urea nitrogen levels and renal damage induced by LPS; this was coincident with reduced expression of HDAC4, a major isoform of class IIa HDACs, and elevated histone H3 acetylation. TMP195 treatment following LPS exposure also reduced renal tubular cell apoptosis and attenuated renal expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1, two biomarkers of tubular injury. Moreover, LPS exposure resulted in increased expression of BAX and cleaved caspase-3 and decreased expression of Bcl-2 and bone morphogenetic protein-7 in vivo and in vitro; TMP195 treatment reversed these responses. Finally, TMP195 inhibited LPS-induced upregulation of multiple proinflammatory cytokines/chemokines, including intercellular adhesion molecule-1, monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-1β, and accumulation of inflammatory cells in the injured kidney. Collectively, these data indicate that TMP195 has a powerful renoprotective effect in SA-AKI by mitigating renal tubular cell apoptosis and inflammation and suggest that targeting class IIa HDACs might be a novel therapeutic strategy for the treatment of SA-AKI that avoids the unintended adverse effects of a pan-HDAC inhibitor.

Protein acetylation and deacetylation: An important regulatory modification in gene transcription (Review)

Cells primarily rely on proteins to perform the majority of their physiological functions, and the function of proteins is regulated by post-translational modifications (PTMs). The acetylation of proteins is a dynamic and highly specific PTM, which has an important influence on the functions of proteins, such as gene transcription and signal transduction. The acetylation of proteins is primarily dependent on lysine acetyltransferases and lysine deacetylases. In recent years, due to the widespread use of mass spectrometry and the emergence of new technologies, such as protein chips, studies on protein acetylation have been further developed. Compared with histone acetylation, acetylation of non-histone proteins has gradually become the focus of research due to its important regulatory mechanisms and wide range of applications. The discovery of specific protein acetylation sites using bioinformatic tools can greatly aid the understanding of the underlying mechanisms of protein acetylation involved in related physiological and pathological processes.

A review of myocardial ischaemia/reperfusion injury: Pathophysiology, experimental models, biomarkers, genetics and pharmacological treatment

Cardiovascular diseases are known to be the most fatal diseases worldwide. Ischaemia/reperfusion (I/R) injury is at the centre of the pathology of the most common cardiovascular diseases. According to the World Health Organization estimates, ischaemic heart disease is the leading global cause of death, causing more than 9 million deaths in 2016. After cardiovascular events, thrombolysis, percutaneous transluminal coronary angioplasty or coronary bypass surgery are applied as treatment. However, after restoring coronary blood flow, myocardial I/R injury may occur. It is known that this damage occurs due to many pathophysiological mechanisms, especially increasing reactive oxygen types. Besides causing cardiomyocyte death through multiple mechanisms, it may be an important reason for affecting other cell types such as platelets, fibroblasts, endothelial and smooth muscle cells and immune cells. Also, polymorphonuclear leukocytes are associated with myocardial I/R damage during reperfusion. This damage may be insufficient in patients with co-morbidity, as it is demonstrated that it can be prevented by various endogenous antioxidant systems. In this context, the resulting data suggest that optimal cardioprotection may require a combination of additional or synergistic multi-target treatments. In this review, we discussed the pathophysiology, experimental models, biomarkers, treatment and its relationship with genetics in myocardial I/R injury. SIGNIFICANCE OF THE STUDY: This review summarized current information on myocardial ischaemia/reperfusion injury (pathophysiology, experimental models, biomarkers, genetics and pharmacological therapy) for researchers and reveals guiding data for researchers, especially in the field of cardiovascular system and pharmacology.

Histone Deacetylase Inhibitor Suberoylanilide Hydroxamic Acid Improves Energetic Status and Cardiomyogenic Differentiation of Human Dilated Myocardium-Derived Primary Mesenchymal Cells

Background. In this study the effect of histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) on the energetic status and cardiomyogenic differentiation of human healthy and dilated myocardium-derived mesenchymal stromal cells (hmMSC) have been investigated. Methods. The hmMSC were isolated from the healthy and dilated post-operation heart biopsies by explant outgrowth method. Cell proliferation, HDAC activity, mitochondrial membrane potential, and level of adenosine triphosphate (ATP) were evaluated. The effect of SAHA on mitochondrial parameters has been investigated also by Seahorse XF analyzer and cardiomyogenic differentiation was confirmed by the expression of transcription factor NK2 Homeobox 5 (Nkx2.5), cardiac troponin T and alpha cardiac actin at gene and protein levels. Results. Dilated myocardium-derived hmMSC had almost 1.5 folds higher HDAC activity compared to the healthy cells and significantly lower mitochondrial membrane potential and ATP level. HDAC class I and II inhibitor SAHA improved energetic status of mitochondria in dilated myocardium-isolated hmMSC and increased expression of cardiac specific proteins during 14 days of exposure of cells to SAHA. Conclusions. HDAC inhibitor SAHA can be a promising therapeutic for dilated cardiomyopathy (DCM). Dilated hmMSC exposed to SAHA improved energetic status and, subsequently, cardiomyogenic differentiation. Data suggest that human dilated myocardium-derived MSC still have cardio tissue regenerative potential, which might be stimulated by HDAC inhibitors.

Exercise improves cardiac function and glucose metabolism in mice with experimental myocardial infarction through inhibiting HDAC4 and upregulating GLUT1 expression

This study aims to determine the effect of exercise on the cardiac function, metabolic profiles and related molecular mechanisms in mice with ischemic-induced heart failure (HF). HF was induced by myocardial infarction (MI) in C57BL6/N mice. Cardiac function and physical endurance were improved in HF mice after exercise. Micro-PET/CT scanning revealed enhanced myocardial glucose uptake in vivo in HF mice after exercise. Exercise reduced mitochondrial structural damage in HF mice. Cardiomyocytes isolated from HF + exercise mice showed increased glycolysis capacity, respiratory function and ATP production. Both mRNA and protein expression of glucose transporter 1 (GLUT1) were upregulated after exercise. Results of ChIP-PCR revealed a novel interaction between transcription factor myocyte enhancer factor 2a (MEF2a) and GLUT1 in hearts of HF + exercise mice. Exercise also activated myocardial AMP-activated protein kinase (AMPK), which in turn phosphorylated histone deacetylase 4 (HDAC4), and thereby modulated the GLUT1 expression through reducing its inhibition on MEF2a in HF mice. Inhibition of HDAC4 also improved cardiac function in HF mice. Moreover, knockdown of GLUT1 impaired the systolic and diastolic function of isolated cardiomyocytes. In conclusion, exercise improves cardiac function and glucose metabolism in HF mice through inhibiting HDAC4 and upregulating GLUT1 expression.

HDAC inhibition induces autophagy and mitochondrial biogenesis to maintain mitochondrial homeostasis during cardiac ischemia/reperfusion injury

AIMS

The FDA-approved histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA, Vorinostat) has been shown to induce cardiomyocyte autophagy and blunt ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, the precise mechanisms underlying the cardioprotective activity of SAHA are unknown. Mitochondrial dysfunction and oxidative damage are major contributors to myocardial apoptosis during I/R injury. We hypothesize that SAHA protects the myocardium by maintaining mitochondrial homeostasis and reducing reactive oxygen species (ROS) production during I/R injury.

METHODS

Mouse and cultured cardiomyocytes (neonatal rat ventricular myocytes and human embryonic stem cell-derived cardiomyocytes) I/R models were used to investigate the effects of SAHA on mitochondria. ATG7 knockout mice, ATG7 knockdown by siRNA and PGC-1α knockdown by adenovirus in cardiomyocytes were used to test the dependency of autophagy and PGC-1α-mediated mitochondrial biogenesis respectively.

RESULTS

Intact and total mitochondrial DNA (mtDNA) content and mitochondrial mass were significantly increased in cardiomyocytes by SAHA pretreatment before simulated I/R. In vivo, I/R induced >50% loss of mtDNA content in the border zones of mouse hearts, but SAHA pretreatment and reperfusion treatment alone reverted mtDNA content and mitochondrial mass to control levels. Moreover, pretreatment of cardiomyocytes with SAHA resulted in a 4-fold decrease in I/R-induced loss of mitochondrial membrane potential and a 25%-40% reduction in cytosolic ROS levels. However, loss-of-function of ATG7 in cardiomyocytes or mouse myocardium abolished the protective effects of SAHA on ROS levels, mitochondrial membrane potential, mtDNA levels, and mitochondrial mass. Lastly, PGC-1α gene expression was induced by SAHA in NRVMs and mouse heart subjected to I/R, and loss of PGC-1α abrogated SAHA's mitochondrial protective effects in cardiomyocytes.

CONCLUSIONS

SAHA prevents I/R induced-mitochondrial dysfunction and loss, and reduces myocardial ROS production when given before or after the ischemia. The protective effects of SAHA on mitochondria are dependent on autophagy and PGC-1α-mediated mitochondrial biogenesis.

HDAC inhibition as a therapeutic strategy in myocardial ischemia/reperfusion injury

Reperfusion injury during myocardial infarction accounts for approximately half of final infarct size. Whereas this has been known for decades, efficacious therapy targeting reperfusion injury remains elusive. Many proteins are subject to reversible acetylation, and drugs targeting enzymes that govern these events have emerged in oncology. Among these, small molecules targeting protein deacetylating enzymes, so-called histone deacetylases (HDACs), are approved for human use in rare cancers. Now, work emerging from multiple laboratories, and in both mice and large animals, has documented that HDAC inhibition using compounds approved for clinical use confers robust cardioprotection when delivered at the time of myocardial reperfusion. Here, we summarize the key underpinnings of this science, discuss potential mechanisms, and provide a framework for a first-in-human clinical trial.

Targeting autophagy in cardiac ischemia/reperfusion injury: A novel therapeutic strategy

Acute myocardial infarction (AMI) is one of the leading causes of morbidity worldwide. Myocardial reperfusion is known as an effective therapeutic choice against AMI. However, reperfusion of blood flow induces ischemia/reperfusion (I/R) injury through different complex processes including ion accumulation, disruption of mitochondrial membrane potential, the formation of reactive oxygen species, and so forth. One of the processes that gets activated in response to I/R injury is autophagy. Indeed, autophagy acts as a "double-edged sword" in the pathology of myocardial I/R injury and there is a controversy about autophagy being beneficial or detrimental. On the basis of the autophagy effect and regulation on myocardial I/R injury, many studies targeted it as a therapeutic strategy. In this review, we discuss the role of autophagy in I/R injury and its targeting as a therapeutic strategy.